tuning problem

I just got my 77 mgb running again. I had to rebuild the carb because of a bad diaphragm that I ruined. It runs, but at low rpm it hesitates and loses power. I thought it was running too lean, but I've tried to enrich the mixture but it doesn't seem to make any difference. The idle is rough, but even cold with the choke on full it still hesitates. Once I get to about 2000 rpm though, it seems to even out and run strong. But up to 2000 rpm it's shaky at best. I'd appreciate anyone's input or ideas. Thanks.

Your next step is to hook up a vacuum gauge. At idle - which never happens for you - your engine should be pulling at least 14 - 18 lbs./in squared. If you don't have enough vacuum at lower rpm your engine will not be able to Idle correctly.
Causes for low idle vacuum can be an intake leak, leaky valves, wrong valve timing, and wrong ignition timing (retarded or advanced (I am not sure which of the two look it up in a shop manual)).
That's not to say your problem is low vacuum - you have to do some diagnostics and tell me the results.

DID YOU CLEAN THE SPACER AND PLATE OF ALL GASKET MATERIAL SUPER CLEAN AND PUT NEW GASKETS IN I THINK THERE'S 3 OR 4 OF EM.DID YOU PRE SET THE MIXTURE NEEDLE I BELIEVE IT'S FLUSH TO START OUT THEN YOU NEED SPECIAL TOOL TO ADJUST.If you have some spray carb cleaner you can spray around the carb and manifold to find a vacuum leak when its runnig. The engine will smooth out when spray hits vacuum leak.Don't overdo the spraying I had a mechanic catch a BMW on fire by going crazy with the spray.I've had chokes mess up on me before and give all kind of problems. Check and see if everything is free and operating correctly and gasket's good between carb and choke. mgbss63

Is there oil in the damper?

For ZS choke repair look at this site;
http://www.paulbunyan.net/~jasko/choke/
It has step by step instructions and good photos.
A bad brake servo can cause vacuum leaks, remove the hose from the servo and cap or plug the hose and see if it will idle. It does sound like you may have a vacuum leak.

All these comments assume the engine is in good tune. If you aren't sure you should do a complete tune up to include, valve adjustment, compression test and ignition timing.

Do you have any coolant loss?
Does the engine smoke?
Any signs of coolant in the oil?

Clifton